The invention is directed to a process for the production of adhesive metal coatings applied chemically, by evaporation in vacuum or by sputtering to electrical non-conductors, especially synthetic resins, by roughening the surface regions to be coated by means of a preliminary etching before the metallization.
Metallized non-conductors, especially metallized synthetic resins, find many uses in all areas of technology. The metal coatings are produced by evaporation, chemical deposition or by pasting or rolling onto films.
Insofar as the metallization is not only for decorative purposes, the adhesiveness of the metal coating is always of greater importance.
There are known various processes for increasing the adhesiveness of the metal coatings before the metallization. This occurs above all through roughening of the surface to be coated by means of buffing processes, impressing a relief in the surface, swelling and roughening the surface by means of acids, alkalis or solvents, use of adhesion facilitating intermediate layers (varnishes, pastes), by means of acids or alkalis embedding foreign materials in the adhesive facilitator which foreign materials can be dissolved out (cavity formation), or through evaporation of the adhesion facilitating intermediate layers.
For the cases of use in which the metal coating must have a defined adhesiveness in the range of greater than 1.2 n/mm, previously sufficient values were produced only through the use of paste systems or adhesion facilitators.
However, even with these adhesion facilitators and adhesive systems, the adhesives frequently prove insufficient in the later processing of the materials, particularly in thermal requirements. This concerns specifically all materials with paste systems. For example the paste causes problems in later soldering processes or bonding processes if such materials are used for the production of printed circuits. Furthermore, pastes and adhesive facilitators are expensive and can only be applied uniformly at high expense.
Therefore it was the problem of the present invention to develop a process for the production of adhesive metallic coatings applied chemically, by evaporation in a vacuum or by sputtering on non-conductors, especially on synthetic resins, by roughening the surface region to be coated by means of a preliminary etching before the metallization through which a very high adhesiveness of the metal coating is attained, even without the use of adhesive facilitating intermediate layers.